The present invention relates generally to the field of vital proteins, and more specifically to viral proteins having immunoregulatory activity.
Viruses are infectious particles which contain genetic elements that enable the virus to replicate within a living host cell. By sequencing the genes of viruses and analyzing the DNA sequence, it has been possible to identify many open reading frames (ORFs) comprising long stretches of triplet codons beginning with a translation-initiation codon (preceded by a ribosomal binding site) and uninterrupted by a translational stop codon. Most ORFs in viruses, however, have not been shown to code proteins. For example, the genomic organization and DNA sequence of several ORFs from the telomeric region of Shope fibroma virus (SFV) have recently been characterized (Upton et al.,Virology 160:20 (1987)). Although it has been shown that these ORFs are transcriptionally active and code for mRNAs, no proteins encoded by these mRNAs have yet been identified or isolated, nor has any biological function for the putative proteins (as surmised from the ORF) been identified. Similarly, the DNA sequence of telomeric region of the myxoma virus has been obtained and several DRFs identified; however, no protein encoded by these ORFs has been identified, isolated or characterized.
The present invention identifies a specific class of vital proteins having innnunosuppressive activity, and provides a method for identifying and isolating such viral proteins. The invention also provides pharmaceutical compositions for regulating immune responses.